Institute of Medical Virology, University of Zurichgrid.7400.3, Zurich, Switzerland.
Life Science Zurich Graduate School, ETH and University of Zurichgrid.7400.3, Zurich, Switzerland.
Microbiol Spectr. 2022 Aug 31;10(4):e0092122. doi: 10.1128/spectrum.00921-22. Epub 2022 Jul 14.
Influenza A virus (IAV) coopts numerous host factors for efficient replication. The cysteine protease cathepsin W (CTSW) has been identified as one host factor required for IAV entry, specifically for the escape of IAVs from late endosomes. However, the substrate specificity of CTSW and the proviral mechanism are thus far unknown. Here, we show that intracellular but not secreted CTSW promotes viral entry. We reveal 79 potential direct and 31 potential indirect cellular target proteins of CTSW using the high-throughput proteomic approach terminal amine isotopic labeling of substrates (TAILS) and determine the cleavage motif shared by the substrates of CTSW. Subsequent integration with data from RNA interference (RNAi) screens for IAV host factors uncovers first insights into the proviral function of CTSW. Notably, CTSW-deficient mice display a 25% increase in survival and a delay in mortality compared to wild-type mice upon IAV infection. Altogether, these findings support the development of drugs targeting CTSW as novel host-directed antiviral therapies. Influenza viruses are respiratory pathogens and pose a constant threat to human health. Although antiviral drugs are available for influenza, the emergence and spread of drug-resistant viruses is cause for concern. Therefore, the development of new antivirals with lower chances of their target viruses acquiring resistance is urgently needed to reduce the high morbidity and mortality caused by influenza. Promising alternatives to drugs targeting viral proteins are those directed against host factors required for viral replication. The cysteine protease cathepsin W (CTSW) is an important host factor for IAV replication, and its proteolytic activity is required for fusion of viral and endosomal membranes. In this work, we identify a number of hitherto unknown CTSW substrates, providing new insights into virus-host interactions, and reveal that CTSW might also play a proviral role in an model. These results support the development of CTSW as a drug target for next-generation antivirals against influenza.
甲型流感病毒（IAV）会利用许多宿主因子来实现高效复制。半胱氨酸蛋白酶组织蛋白酶 W（CTSW）已被鉴定为 IAV 进入所需的宿主因子之一，特别是 IAV 从晚期内体逃逸所需的宿主因子。然而，CTSW 的底物特异性和促病毒作用机制目前尚不清楚。在这里，我们发现细胞内而非分泌型的 CTSW 可促进病毒进入。我们使用高通量蛋白质组学方法末端胺同位素标记的底物（TAILS）揭示了 79 个潜在的 CTSW 直接和 31 个潜在的间接细胞靶蛋白，并确定了 CTSW 底物的共同切割基序。随后与 IAV 宿主因子的 RNA 干扰（RNAi）筛选数据相结合，首次揭示了 CTSW 的促病毒作用。值得注意的是，与野生型小鼠相比，CTSW 缺陷型小鼠在感染 IAV 后存活率提高了 25%，且死亡时间延迟。总之，这些发现支持开发针对 CTSW 的药物作为新型宿主定向抗病毒疗法。
流感病毒是呼吸道病原体，对人类健康构成持续威胁。尽管有抗病毒药物可用于治疗流感，但耐药病毒的出现和传播令人担忧。因此，迫切需要开发新的抗病毒药物，以降低流感引起的高发病率和死亡率，这些药物的靶点不太可能被其靶病毒获得耐药性。针对病毒蛋白的药物的有前途替代品是针对病毒复制所需的宿主因子的药物。半胱氨酸蛋白酶组织蛋白酶 W（CTSW）是 IAV 复制的重要宿主因子，其蛋白水解活性对于病毒和内体膜的融合是必需的。在这项工作中，我们鉴定了一些迄今未知的 CTSW 底物，为病毒-宿主相互作用提供了新的见解，并揭示 CTSW 可能在模型中也发挥着促病毒作用。这些结果支持将 CTSW 作为针对流感的下一代抗病毒药物的靶标进行开发。
